A Flagella Hook Coding Gene flgE Positively Affects Biofilm Formation and Cereulide Production in Emetic Bacillus cereus

Abstract

Bacillus cereus, an important foodborne pathogen, poses a risk to food safety and quality. Robust biofilm formation ability is one of the key properties that is responsible for the food contamination and food poisoning caused by B. cereus, especially the emetic strains. To investigate the mechanism of biofilm formation in emetic B. cereus strains, we screened for the mutants that fail to form biofilms by using random mutagenesis toward B. cereus 892-1, an emetic strain with strong biofilm formation ability. When knocking out flgE, a flagellar hook encoding gene, the mutant showed disappearance of flagellar structure and swimming ability. Further analysis revealed that both pellicle and ring presented defects in the null mutant compared with the wild-type and complementary strains. Compared with the flagellar paralytic strains ΔmotA and ΔmotB, the inhibition of biofilm formation by ΔflgE is not only caused by the inhibition of motility. Interestingly, ΔflgE also decreased the synthesis of cereulide. To our knowledge, this is the first report showing that a flagellar component can both affect the biofilm formation and cereulide production in emetic B. cereus, which can be used as the target to control the biohazard of emetic B. cereus.

Sigma factor RpoS positively affects the spoilage activity of Shewanella baltica and negatively regulates its adhesion effect

“…The secretion of FlgM indicates the accomplishment of the Hookbasal body (Wosten et al, 2010). The function of FlgE is to connect the flagellum filament and hook, which changes the angle of flagellum rotation (Shen et al, 2017;Li et al, 2022). Previous studies showed that the enhanced motility of rpoS mutant required the RpoN, and about 60% of genes were simultaneously oppositely regulated by RpoS and RpoN (Dong and Schellhorn, 2010).…”

“…Bacterial TCRS is involved in the regulation of bacterial chemotaxis, morphological differentiation, nutrient metabolism, drug resistance, and many other physiological processes. Li et al (2022) showed that the expression of rpoS can be activated by the two-component system of TorR using transcriptomics, while the effect of RpoS on TCRS was rarely studied. The up-regulated TCRS in the rpoS mutant indicated that TCRS is involved in the stress regulation of RpoS to S. baltica, but the detailed mechanism needs to be further explored.…”

Investigating the Role of OrbF in Biofilm Biosynthesis and Regulation of Biofilm-Associated Genes in Bacillus cereus BC1

“…This regulation influences microbial behaviors such as biofilm formation, acid resistance, production of antimicrobial factors, and the control of virulence factor expression, contributing to food spoilage and bacterial pathogenicity issues [ 14 , 15 ]. Ding’s research group at Jinan University, through transposon random mutagenesis, discovered that the deletion of the flgE gene in B. cereus inhibits biofilm formation [ 16 ]. Slack et al [ 17 ], by performing in-frame deletion of the clpY gene, enhanced biofilm formation.…”

“…Mutant strains with impaired biofilm synthesis were selected. Through reverse PCR identification of these selected B. cereus mutants, the disrupted genes were identified, revealing the involvement of the RNA polymerase sigma factor SigB encoding gene J8Y18_05105 , as well as genes related to flagellum synthesis and secretion, including flgG [ 21 ], flgE [ 16 ], motB [ 22 ], the adenylyl cyclase encoding gene J8Y18_20970 , and the TIGR04197 family type VII secretion effector encoding gene J8Y18_14985 . Additionally, three previously uncharacterized transcriptional regulatory factor encoding genes J8Y18_01585 , J8Y18_16035 , and J8Y18_09555 were identified.…”

A Quick DNA Extraction Method for High Throughput Screening in Gram-positive Bacteria

“…This protocol was adapted from previous work ( Chen et al, 2022 ; Li et al, 2022 ). This research was supported by Guangdong Major Project of Basic and Applied Basic Research (2020B0301030005), Guangdong Provincial Key Laboratory (2020B121201009), and Guangdong Province Academy of Sciences Special Project for Capacity Building of Innovation Driven Development (2020GDASYL-20200301002).…”